The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole

One of the most intriguing scenarios proposed to explain how active galactic nuclei are triggered involves the existence of a supermassive binary black hole system in their cores. Here we present an observational evidence for the first spectroscopically resolved sub-parsec orbit of a such system in the core of Seyfert galaxy NGC 4151. Using a method similar to those typically applied for spectroscopic binary stars we obtained radial velocity curves of the supermassive binary system, from which we calculated orbital elements and made estimates about the masses of components. Our analysis shows that periodic variations in the light and radial velocity curves can be accounted for an eccentric, sub-parsec Keplerian orbit of a 15.9-year period. The flux maximum in the lightcurve correspond to the approaching phase of a secondary component towards the observer. According to the obtained results we speculate that the periodic variations in the observed H{\alpha} line shape and flux are due to shock waves generated by the supersonic motion of the components through the surrounding medium. Given the large observational effort needed to reveal this spectroscopically resolved binary orbital motion we suggest that many such systems may exist in similar objects even if they are hard to find. Detecting more of them will provide us with insight into black hole mass growth process.Comment: 29 pages, 10 figures, published in ApJ, 759, 11

Variability of the H-beta line profiles as an indicator of orbiting bright spots in accretion disks of quasars: a case study of 3C 390.3

Here we show that in the case when double peaked emission lines originate from outer parts of accretion disk, their variability could be caused by perturbations in the disk emissivity. In order to test this hypothesis, we introduced a model of disk perturbing region in the form of a single bright spot (or flare) by a modification of the power law disk emissivity in appropriate way. The disk emission was then analyzed using numerical simulations based on ray-tracing method in Kerr metric and the corresponding simulated line profiles were obtained. We applied this model to the observed H-beta line profiles of 3C 390.3 (observed in the period 1995-1999), and estimated the parameters of both, accretion disk and perturbing region. Our results show that two large amplitude outbursts of the H-beta line observed in 3C 390.3 could be explained by successive occurrences of two bright spots on approaching side of the disk. These bright spots are either moving, originating in the inner regions of the disk and spiralling outwards by crossing small distances during the period of several years, or stationary. In both cases, their widths increase with time, indicating that they most likely decay.Comment: 14 pages, 5 figures, 1 table. Accepted for publication in Ap

The influence of antero-posterior dentoskeletal pattern on the value of nasal soft tissue angles: a cephalometric study

Background: The aim of this study was to examine the influence of sagittal dentoskeletal pattern on the value of profile nasal soft tissue angles and estimate the significance of examined differences for each angle.Materials and methods: Lateral cephalograms were used to examine the nasofrontal angle, nasofacial angle, nasal tip angle, and nasolabial angle of 120 adult Caucasian subjects (60 male and 60 female) from the central Balkan area. Subjects were divided into four groups according to the ANB angle and incisors inclination: class I as the control group, class II division 1, class II division 2 and class III.Results: By evaluating the influence of sagittal dentoskeletal relationships on the values of examined angles, significant differences were found among subjects with class I and class II/2 (p = 0.028), so as class III (p = 0.002) for nasal tip angle. The nasofacial angle was found to differ among subjects with class I and class II/1 (p = 0.002), so as class III (p = 0.001).Conclusions: Different dentoskeletal patterns have significant influence on values of the nasal tip angle and nasofacial angle, and don’t have influence on the values of the nasofrontal and nasolabial angle

The Exchange of Tritiated Water Between Zn-A Zeolitevand the Surrounding Water

Zeolites are considered as adsorbents for tritiated waste water. The sorption capacity of 4A zeolite is increased, and the speed of tritium release, as THO, decreased if sodium ions in 4A zeolite are replaced with small divalent cations. The exchange kinetics THO/H20 between Zn-A zeolite containing tritiated water and the surrounding water was investigated at 30-60 De, using zinc-exchanged 4A zeolite beads of 0.8 and 1.6 mm radius. The kinetics was controlled by the diffusion of water in the solid particle and interpreted in terrns of the Boyd - Reichenberg diffusion model. Effective self-diffusion coefficients of water in the zeolite beads were obtained and the kinetic data are discussed from the point of view of using zeolites as sorbents and storage material for tritiated waste water

A data comparison between a traditional and the single-step β-galactosidase assay

This article describes reproducibility of a single-step automated β-galactosidase, and the equivalence of its data to the traditional assay ("Experiments in Molecular Genetics" [1]). This was done via a pairwise comparison of both methods using strains with Miller Unit [MU] values ranging from 0 to over 2000. The data presented in this article is associated with the research article entitled "A single-step method for mid to high throughput β-galactosidase assays in Escherichia coli using a microplate reader" [2]

FARE: Provably Fair Representation Learning with Practical Certificates

Fair representation learning (FRL) is a popular class of methods aiming to produce fair classifiers via data preprocessing. Recent regulatory directives stress the need for FRL methods that provide practical certificates, i.e., provable upper bounds on the unfairness of any downstream classifier trained on preprocessed data, which directly provides assurance in a practical scenario. Creating such FRL methods is an important challenge that remains unsolved. In this work, we address that challenge and introduce FARE (Fairness with Restricted Encoders), the first FRL method with practical fairness certificates. FARE is based on our key insight that restricting the representation space of the encoder enables the derivation of practical guarantees, while still permitting favorable accuracy-fairness tradeoffs for suitable instantiations, such as one we propose based on fair trees. To produce a practical certificate, we develop and apply a statistical procedure that computes a finite sample high-confidence upper bound on the unfairness of any downstream classifier trained on FARE embeddings. In our comprehensive experimental evaluation, we demonstrate that FARE produces practical certificates that are tight and often even comparable with purely empirical results obtained by prior methods, which establishes the practical value of our approach.Comment: ICML 202

Evaluation of antimicrobial and cytotoxic potential of ethanol extracts isolated from selected plants of Polygonoideae subfamily and their effect in combination with streptomycin and doxorubicin

Za ispitivanje antimikrobnog i citotoksičnog efekta odabrano je 8 biljaka podfamilije Polygonoideae od kojih je napravljeno 12 etanolnih ekstrakata, od herbi (h) i rizoma (r): Polygonum aviculare (POAh, POAr), Polygonum maritimum (POMh), Persicaria amphibia (PEAh), Persicaria maculosa (PEMh), Persicaria lapathifolia (PELh, PELr), Persicaria hydropiper (PEHh, PEHr), Bistorta officinalis (BIOh, BIOr) i Fagopyrum esculentum (FAEh). Svi testirani ekstrakti ispoljavaju umerenu antifungalnu aktivnost, a POAh, POMh, PEAh, POAr, PEHr i BIOr dovode do obezbojavanja konidija. Antibakterijski efekat je testiran prema većem broju G+ i G- bakterija pri čemu je BIOr pokazao najpotentnije antimikrobno dejstvo. BIOr i PEMh pokazuju značajan antibiofilm i antiquorum sensing efekat prema medicinski važnom patogenu Pseudomonas aeruginosa PAO1 i to preko modulacije aktivnosti LasR receptora. Ovi ekstrakti i njihovi aktivni konstituenti, hinska i hlorogenska kiselina, katehin i kvercetin- 3-O-glukozid, inhibiraju sintezu violaceina kod Chromobacterium violaceum. U kombinaciji sa streptomicinom BIOr ostvaruje različite tipove interakcija: antagonistički, indiferentni, aditivni i sinergistički. Prilikom testiranja citotoksičnosti odabranih ekstrakata i doksorubicina (D) uočen je sinergizam između P. aviculare i D na ćelijama hepatocelularnog adenokarcinoma (HepG2) i plućnog adenokarcinoma (A549). Takođe, sinergizam između P. amphibia i D je detektovan na A549 ćelijama. Sinergistički efekat se ostvaruje preko sledećih procesa: uvođenje ćelija u apoptozu, zaustavljanje ćelijskog ciklusa, modelovanje aktivnosti antioksidativnih enzima i Keap1-Nrf2 signalnog puta. Na normalnim ćelijama fibroblasta pluća (MRC-5) P. aviculare i D, P. amphibia i D kao i P. maculosa i D ostvaruju antagonizam. Odsustvo toksičnosti PEMh i BIOr u nižim dozama, potvrđeno je in vivo testom na modelu Danio rerio.were selected and 12 ethanol extracts were made. Herb (h) and rhizome (r) extracts were obtained from: Polygonum aviculare (POAh, POAr), Polygonum maritimum (POMh), Persicaria amphibia (PEAh), Persicaria maculosa (PEMh), Persicaria lapathifolia (PELh, PELr), Persicaria hydropiper (PEHh, PEHr), Bistorta officinalis (BIOh, BIOr) and Fagopyrum esculentum (FAEh). All tested extracts moderately inhibited the growth of selected fungi. POAh, POMh, PEAh, POAr, PEHr and BIOr leads to discoloration of conidia. Antibacterial activity on different Gram positive and Gram negative strains has been evaluated. BIOr showed the most potent antibacterial activity. Also, BIOr and PEMh exhibited significant antibiofim and antiquorum sensing effects against medically important pathogen, Pseudomonas aeruginosa PAO1, through the modulation of LasR receptor activity. Both extracts as well as their active constituents, chinic acid, chlorogenic acid, catechin and quercetin-3-O-glucoside, inhibited violacein synthesis in Chromobacterium violaceum. The BIOr engaged in various interactions with streptomycin: synergic, addictive, indifferent and antagonistic. Cytotoxicity testing of selected extracts and doxorubicin (D) revealed a synergistic relationship between P. aviculare and D, in hepatocellular adenocarcinoma (HepG2) and pulmonary adenocarcinoma cells (A549). Also, synergism between P. amphibia and D, was detected on A549 cells. The observed synergisms could be linked to the interference with apoptosis, cell cycle, antioxidant enzymes expression and Keap1-Nrf2 pathway. On normal lung fibroblast cells (MRC-5) P. aviculare and D, P. amphibia and D as well as P. maculosa and D exerts an antagonistic effect. In vivo assay on the Danio rerio model shows no signs of toxicity at lower tested concentrations for PEMh and BIOr

Metal rings and discs Matlab/Simulink 3D model for ultrasonic sandwich transducer design

Metal-endings are integral part of different ultrasonic sandwich transducers. In this paper a new Matlab/Simulink 3D model of the finite metal rings and discs of various dimensions is realized. With this model, which describes both the thickness and the radial resonant modes, and the coupling between them, mechanical impedance of the sample can be easily computed. Resonance frequency-length curves for rings and disks with various materials and for different selected dimensions are given. Also, comparisons of the different approaches in determining of their resonant frequencies are shown. The proposed Matlab/Simulink model requires simpler implementation than other analytical models. That enabled modifying of 1D theory and simplified modelling and projecting of the ultrasonic sandwich transducers with short-endings. Finally, the computed and experimental results are compared. [Projekat Ministarstva nauke Republike Srbije, br. TR33035, br. III43014 i br. OI172057

Crack initiation and propagation resistance of hsla steel welded joint constituents

The welded joint is heterogeneous in its microstructure, mechanical and geometrical properties, thus the stress field is affected by different factors as well as by residual stress. Therefore, special procedures are needed for experimentally determining the fracture toughness in plane strain, K-Ic, and the impact toughness, usually associated with difficulties in interpreting the measured values. Notched specimens are tested by instrumented Charpy in order to determine impact energy and crack initiation and propagation energies. The pre-cracked specimens are tested by standard, using three-point bending specimens, as geometrically closest to Charpy specimens. In both cases, the notch and crack are located in all various regions of the welded joint of the high-strength low alloyed steel NIONIKRAL-70. Analysis of the results includes speculations on the ratio of energies for crack initiation and propagation vs. fracture toughness

Crack initiation and propagation resistance of hsla steel welded joint constituents

The welded joint is heterogeneous in its microstructure, mechanical and geometrical properties, thus the stress field is affected by different factors as well as by residual stress. Therefore, special procedures are needed for experimentally determining the fracture toughness in plane strain, K-Ic, and the impact toughness, usually associated with difficulties in interpreting the measured values. Notched specimens are tested by instrumented Charpy in order to determine impact energy and crack initiation and propagation energies. The pre-cracked specimens are tested by standard, using three-point bending specimens, as geometrically closest to Charpy specimens. In both cases, the notch and crack are located in all various regions of the welded joint of the high-strength low alloyed steel NIONIKRAL-70. Analysis of the results includes speculations on the ratio of energies for crack initiation and propagation vs. fracture toughness